Centrifugal air compressor

ABSTRACT

A centrifugal supercharger is disclosed that includes an internal drive mechanism which embodies the present invention. A pair of sprockets are connected to parallel input and output drive shafts and drivingly connected by a taut, high tension, endless cog-belt seated and running on the two sprockets. A plurality of belt stabilizing components are incorporated therein to provide maintenance-free, low-temperature operation of the drive mechanism. These stabilizing components include air ducts formed in the output sprocket, tensioning members formed in the belt, heat-resistant and high-speed ceramic ball bearings and shock absorbing springs that alone and in combination provide a highly efficient drive mechanism.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates broadly to an internal drivemechanism in an air compressor and, more specifically, to a drivemechanism for use in a supercharger for an internal combustion engine oran air compressor of the type driven mechanically by the engine or otherpower source.

[0003] 2. Discussion of the Prior Art

[0004] It is well known that in a supercharger or air compressor,increasing the volume of air charge delivered to the combustion chamberof an internal combustion engine will increase the output of the enginefor a given displacement at a given engine speed. There are two basictypes of superchargers, centrifugal and positive displacement. Thecentrifugal type is very efficient, providing the best ratio betweenunit dimensions and flow volume. The air compression in the centrifugaldesign is achieved using a scroll or scroll-shaped air chamber having acentrally located air inlet and an impeller rotatably disposed in theair inlet to draw in air and then the compress the air within thescroll. An air outlet connected to the combustion chamber delivers thecompressed air to the engine. Centrifugal designs require highperipheral compressor-wheel or impeller velocities approaching orexceeding the speed of sound, which can be achieved with either anexhaust-driven direct-drive turbine compressor wheel combination, or amechanical drive connected between the engine crankshaft and the inputshaft of the supercharger. The overall speed ratio between the impellerand the crankshaft should be, practically, at least nine impellerrotations for every rotation of the crankshaft, and the outer externalmechanical drive is usually limited to a step-up ratio of approximatelythree input shaft rotations for every rotation of the crankshaft. Thus afurther internal step-up mechanism is desired to increase the impellerto three or four additional rotations for every rotation of the inputshaft.

[0005] It is known in air compressors that a step-up ratio of 9 to 1between power sources and the impeller is desirable. Presently thisratio has been attempted using external step-up drives only; however,such configurations result in relatively low speeds and low flow whencompared to an air compressor with an internal step-up drive. Internaldrives have in the past not been considered reliable for this intendeduse.

[0006] Previously known internal drive mechanisms have employedplanetary traction drives, or gear drives. An example of an internalgear drive mechanism is disclosed in U.S. Pat. No. 5,224,459, issued toJames Middlebrook. In general, traction drives or gear drives requirelubrication, causing unwanted heat buildup, which thereby tends toreduce the density of the compressed air discharge. Planetary step-upball and/or race drives require preloading of the mechanism to preventslippage, due to the necessity of lubrication and traction to transmitrotational power. The preloading of these drives and the relatedlubrication causes further intrinsic heat buildup, thus further reducingthe density of the compressed air discharge. Gear drives are undesirablynoisy to operate, usually requiring hot engine oil to lubricate thegears and bearings, causing additional heat buildup, which alsocontributes to a reduction of the air density. In addition, the geardrives must be connected to the engine oil reserve, making them moredifficult to install and maintain.

OBJECTS AND SUMMARY OF THE INVENTION

[0007] The general object of the present invention is to provide, in anair compressor or supercharger, an internal drive mechanism which, ascompared to prior internal drive mechanisms, generates less heat,operates with greater efficiency, requires less energy to operate andfacilitates installation on the engine or other power source.

[0008] A more specific object is to provide an internal drive mechanismthat utilizes a positive-drive cog belt and pre-lubricated bearingsthereby eliminating the need for oil lubrication of the internal drivemechanism and making the supercharger virtually maintenance free.

[0009] Another object is to provide an internal drive mechanism that isrelatively quiet in relation to normal engine noise.

[0010] Yet another object is to provide an internal drive mechanism thatincorporates stabilizing components to reduce tension and stress on thebelt.

[0011] The present invention relates generally to an improvedsupercharger or air compressor that advantageously incorporates aninternal drive mechanism utilizing a pair of sprockets mounted onparallel input and output shafts respectively and drivingly connected bya taut, endless cog-belt trained around and engagingly running on thetwo sprockets. More importantly, the present invention relates toseveral stabilizing components which alone and together serve tostabilize the tension and stress in the belt, thus allowing the belt tobe operated at speeds and under loads that otherwise would destroy thebelt. One such stabilizing component is the means for evacuating airtrapped between the belt and the output sprocket which, at high speeds,adds unnecessary tension to the belt and may even cause the belt todisengage from the output sprocket. Another such stabilizing componentis a pair of springs nested against the respective input and outputdrive shafts to reduce unwanted vibration which may occur duringacceleration or especially severe deceleration of the belt.

[0012] The input shaft is received within the inner races ofpre-lubricated, sealed ball bearings having outer races anchored to thesupercharger housing, and the output shaft is received within the innerraces of double-shielded, pre-lubricated ceramic ball bearings havingouter races anchored to the supercharger housing, thereby eliminatingthe need for oil lubrication. By eliminating oil lubrication, the drivemechanism is made virtually maintenance-free and generates and retainsless heat during operation. The reduced heat means that the drivemechanism produces greater air-flow and consequent horsepower.

[0013] The cog-belt is a conventional endless belt containinglongitudinal tensioning members such as Kevlar™ or black fiberglass, anddrives the impeller at speeds up to and exceeding approximately 40,000revolutions per minute (RPM). At such speeds, belts can be expected tofail, but it was discovered that the ceramic bearings for the outputshaft, the springs reducing vibration in the respective input and outputshafts, and the air ducts incorporated into the output shaft eachindividually and in cooperation function as stabilizing componentscontributing to the operational life of the belt for virtuallymaintenance-free high-speed, operation.

[0014] In addition, an idler is incorporated into the internal drivemechanism to engage the belt. While conventional wisdom suggests thatthe idler should be placed to engage the portion of the belt returningfrom the drive or input shaft, the present invention incorporates theidler to engage the portion of the belt returning from the driven oroutput shaft. The idler stabilizes the belt during deceleration toprevent additional wear to the belt during rapid and uncontrolleddeceleration that can occur under normal stop-and-go traffic conditions.With the idler in its unusual location, the output shaft functions asthe drive shaft during deceleration when the idler is needed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Other objects and advantages of the invention will becomeapparent from the foregoing detailed description taken in connectionwith the accompanying drawings, in which

[0016]FIG. 1 is a front perspective view of a supercharger including aninternal drive mechanism embodying the novel features of the presentinvention;

[0017]FIG. 2 is an exploded perspective view of the supercharger;

[0018]FIG. 3 is a sectional view taken along the line 3-3 of FIG. 1;

[0019]FIG. 4 is an enlarged sectional view taken along the line 4-4 ofFIG. 3;

[0020]FIG. 5 is an enlarged sectional view of the internal drivemechanism of the preferred embodiment taken substantially along line 5-5of FIG. 3;

[0021]FIG. 6 is an enlarged sectional side view of the superchargertaken substantially along line 6-6 of FIG. 1;

[0022]FIG. 7 is an enlarged perspective view of the impeller of thepresent invention; and

[0023]FIG. 8 is an enlarged sectional view similar to FIG. 3 but showingan alternative embodiment of the internal drive mechanism of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] As shown in the drawings for purposes of illustration, theinvention is contained within a conventional supercharger or aircompressor housing of the centrifugal type. The housing includesgenerally a special casing 20 known as the “scroll” 20 (FIGS. 1 and 2)having an air outlet 22 and an air inlet 24 (FIG. 6), a cover 26configured with ribs 28 for strength and for cooling by virtue of theadded surface area, and a case 30 (FIGS. 1 and 2) secured by bolts 32and 34 respectively inserted through threaded bores 36 and 38 betweenthe scroll 20 and the cover 26 respectively. The bolts 32 connectingscroll 20 and the case 30 include retainers 40 connecting between pairsof bolts for added structural support. The scroll 20, the case 30 andcover 26 are preferably made of 356-T6 industry grade cast aluminum.

[0025] The scroll 20 (FIG. 6) and inner wall 42 of the case 30 form aconventional type compression chamber 43 in which the impeller 44includes a rotor 46 aligned coaxially within the cylindrically shapedair inlet 24 to draw air into the compression chamber 43 from the airinlet 24 through the gaps between the rotating blades 48. The impeller44 (FIGS. 6 and 7) includes a base 50 rotatingly nested in a shallowbore 52 in the case wall and a generally triangularly-shaped, fixed hub54 normal to the base 50 and received on a matching triangularly-shapedsegment 56 of a steel output shaft 58 extending through a bore 60coaxial with the shallow bore 52 in the case wall, and held thereon by aretainer 62 and screw 64. The generally triangularly-shaped shaft 56 andmatching hub 54, although this shape is preferred, may be anyconventional shape to prevent movement there between. The impeller ispreferably made of 355-T6 industry grade high density cast aluminum.

[0026] For added structural support and precision alignment between thecase 30 (FIG. 2) and the cover 26, alignment pegs 66 extend from thecase and are received in matching holes (not shown) in the cover. Asteel input shaft 68 (FIGS. 2 and 6), parallel to the output shaft 58,includes a segment 70 extending through a bore 72 in the cover andincludes a slip-fit, key-fixed pulley 74 received on the input shaft 68,positioned adjacent to the cover, and held thereon by a retainer 76 andscrew 78 connected coaxially with the drive shaft in a thread bore. Thepulley 74 is grooved to receive a belt (not shown) drivingly connectedto a pulley located on the drive shaft of an engine (not shown) toobtain a conventional 3-to-1 step-up ratio.

[0027] Advantageously, the internal drive mechanism (FIGS. 2 and 3)which primarily embodies the novel features of this invention iscontained within the drive chamber 80 defined by the inner wall 42 ofthe case, the surrounding elongated portion 82 of a split level rim 84formed about the perimeter of the case wall and the cover. The innerdrive mechanism generally includes an output sprocket 86 and an inputsprocket 88 mounted on the respective output and input shafts 58 and 68and drivingly connected by a taut, endless cog belt 90 seated andrunning on the sprockets 86 and 88 with a tooth profile to match thetooth profile of the sprockets. The belt 90 may be made using Kevlar™ orpreferably black fiberglass as the tensioning member to provide theminimal strength necessary for operation. The cog-tooth belt at aminimum must have an allowable tensile load requirement of approximately150 lbs., an allowable stress requirement in tension generally greaterthan 37,000 psi in the belt minimum cross-section, and an allowableshear stress in a dynamic (vibratory) loading situation of a minimum ofapproximately 2400 psi at the tooth root, and operate within thetemperature range of approximately −30° to +300° Fahrenheit in order todrive the output sprocket at the preferable speed of approximately40,000 RPM plus or minus 7,000 RPM. A belt suitable for this purpose,but not limited to, is manufactured by Gates Rubber Company under U.S.Pat. Nos. 4,233,852 and 4,337,056. It will be appreciated that asimprovements are made to belt technology, these ranges may be increased.The diameters of the input and output sprockets 86 and 88 arepredetermined to provide generally the desired additional 3-to-1 step-upratio.

[0028] The output sprocket 86 (FIGS. 2 and 4) includes radially extendedflanges 92 and 94 on opposite ends of the cylindrical sprocket inclinedaway from each other to form containments wherein the belt 90 engagesthe output sprocket. The output sprocket 86 includes a coaxial bore 96forming a central hub and pairs of spaced apart, radial bores 98 and 100extending from the gaps in the sprocket teeth to the coaxial bore 96forming radial air vents. The sprocket hub is received on a widediameter segment 102 of the output shaft 58. A pair of parallel, spacedapart channels 104 and 106 extend about the circumference of the outputshaft 58 and align with the radial vent bores 98 and 100 to form a pairof radial air ducts constituting means for evacuating air through thesprocket vents between the sprocket gaps. As shown most clearly in FIG.4, these air ducts comprise the vents 98 and 100 in the sprockets andthe channels 104 and 106 of the shaft.

[0029] A pair of shielded, pre-lubricated, ceramic (Silicon-Nitride)ball bearings 108 and 110 include inner races 112 and 114 respectivelyreceived on the output shaft 58 at opposite ends of the output sprocket86. The sealed bearings include outer races 116 and 118 received inopposing anchor bores 120 and 122 (FIG. 6) coaxial with the shaft 58 andbore 60 extending through the case wall into the compression chamber 43.A ceramic bearing typical of the type suitable for this purpose ismanufactured by The Barden Corporation, Danbury, CT and sold under modelnumber C202SST5. Nested between the cover 26 and the outer race 116 ofthe bearing within the cover sleeve is a disk-shaped finger spring 124and a spacer 126 engaging the spring 124 and the bearing outer race 116.

[0030] The input sprocket 88 (FIGS. 2 and 6) made preferably of solid6061-T6 industry grade aluminum includes an outer sprocket rim 128connected to a central hub 130 by a centrally-located, radial disk 132extending therebetween to minimize weight. The input sprocket 88 ispreferably coated with a wear, corrosion and temperature reducingcoating such as Magna Coating™ sold by Gates Rubber Co., Denver, Colo.The input sprocket hub 130 is received on the input shaft 68 and a pairof sealed, pre-lubricated steel bearings 134 and 136 having inner races138 and 140 respectively received on the shaft 68 are positioned alongthe shaft proximate to respective sides of the sprocket 88. The sealedbearings 134 and 136 include outer races 142 and 144 received inopposing anchor sleeves 146 and 148 coaxial to the shaft 68 and bore 72extending through the cover wall to the pulley 74. A steel bearingtypically of the type suitable for this purpose is manufactured byAmerican Koyo Corp., Cleveland, Ohio and sold under model number6205ZZCMP5GK7. Nested between the cover and the outer race of thebearing in the input cover sleeve is a disk-shaped finger spring 150.

[0031] The presently preferred embodiment additionally includes an idler152 (FIGS. 2 and 3) having a central axis 154 normal to the sides 156and 158 of the belt and uniquely seated against the outer surface 160 ofthe belt along the load transfer side of the belt drive. The idler 152includes a pulley 162 having a hub 164 received on the outer races 166and 168 of respective steel ball bearings positioned at opposite ends ofthe pulley 162. The inner races 174 and 176 of the ball bearings 170 and172 are received on a fixed shaft 178 threadedly fixed at a threaded end180 in a threaded bore (not shown) in the case wall. A conventionalfastener, such as a retaining ring 182, may be used to secure the idlerassembly on the shaft 178 at a free end. A partial sleeve 184 formed inthe case rim allows for unobstructed rotation of the idler pulley 162.

[0032] Another novel aspect of the present invention is the use ofdisk-shaped shims 90 (FIG. 6) within the compression chamber 43 betweenthe impeller base 50 and a shoulder 185 of the output shaft 58 having agenerally triangularly-shaped, central bore (not shown) received on theoutput shaft segment 56 and against the shoulder 185 for rotation of theshims with the output shaft in spaced apart relation to the case wall.The shims generally range in thickness from {fraction (2/1,000)} to{fraction (30/1,000)} of an inch and cooperate with the impeller bladesto obtain an impeller clearance with the inner surface of the scroll.The shims allow alignment of the blade edges 48 of the impeller 44 toachieve as closely as possible an impeller clearance within the generalrange of {fraction (7/1,000)} to {fraction (13/1,000)} of inch therebyincreasing efficiency.

[0033] In operation, the supercharger is preferably mounted onto theengine, the air output is connected to the combustion chamber of theengine, and the grooved, outer pulley is drivingly connected to theengine shaft by a belt (not shown). The outer pulley 74 (FIGS. 1 and 2)is configured to run at a speed three times faster than the engine driveshaft. The input shaft sprocket 88 (FIGS. 2 and 3) responsive to therotation of the outer pulley 74 also runs at a speed equivalent to threetimes the engine shaft. The output sprocket 86 drivingly connected tothe input sprocket 88 by the belt 90 is driven to speeds three timesgreater than the input sprocket 88, nine times greater than the driveshaft, at speeds of around 40,000 rpm or more.

[0034] At such speeds, changes in the tension of the belt 90 can causeunwanted vibration in the input and output shafts 68 and 58. Thisvibration is minimized by the pre-load and shock absorbing fingersprings 150 and 124 (FIGS. 2 and 6) nested in the case sleeves 146 and120 respectively. The belt seated on the output sprocket 86 (FIGS. 4 and5) between the flanges 92 and 94 can trap air between the interlockingteeth of the belt 92 and sprocket 86 when operated at such speeds, sothe trapped air can add additional tension to the belt 90 and may evencause the belt 90 to improperly align or disengage. As the belt 90drives the output sprocket 86 in the direction indicated by the arrow195, air trapped in the gaps between the sprocket teeth and the belt isevacuated through the air ducts and out the unobstructed portions of theoutput sprocket 86, as indicated by the arrows 196 in FIG. 5. Aperturescut into the flanges (not shown) may also provide the air evacuationmeans to evacuate the trapped air. In addition, the ceramic ballbearings are preferably rated at speeds up to 62,000-70,000 RPM tomaintain low friction and low heat rotation of the output shaft. Byminimizing the heat on the output shaft, the efficiency of the aircompressor is increased and greater horsepower is achieved in theengine. During acceleration, the loads applied to the belt arecontrolled due to the steadily increasing torque from the engine;however, during deceleration loading is generated by the uncontrolledand chaotic centrifugal forces of the impeller and engine. The idlerfunctions to support the belt during deceleration when the loads appliedto the belt are uncontrolled. All of these improvements, alone and incombination, function as stabling components or stabilizing means.

[0035] An alternatively preferred embodiment (FIG. 8) eliminates theidler where the internal drive mechanism is used with engines other thanfor vehicles, in which sudden deceleration is not experienced. In thisembodiment, which differs from the first embodiment only in the omissionof parts, corresponding elements are indicated by corresponding primedreference numbers and are not otherwise described in detail.

[0036] Air compressors driven by any steady state power source, such asan electric motor, where sudden deceleration is not experienced, do notrequire an idler, but are shown with the other stabilizing components.These internal drives provide additional step-up between the rotation ofthe impeller and the power source thereby increasing efficiency andoutput power.

[0037] While the present invention has been described in connection withwhat are presently considered to be the most practical and preferredembodiments, it is to be understood that the invention is not to belimited to the disclosed embodiments, but to the contrary, is intendedto cover various modifications and equivalent arrangements includedwithin the spirit of the invention, which are set forth in the appendedclaims, and which scope is to be accorded the broadest interpretation soas to encompass all such modifications and equivalent structures.

What is claimed is:
 1. An air compressor apparatus for use as asupercharger in a combustion engine comprising: a case secured to saidengine, a scroll having an air inlet to receive ambient air, an airoutlet connected to said engine to discharge compressed air, and an openend, said case having a wall connected to said open end of said scrollto form an air compression chamber therein and a rim formed about theperimeter of said case wall extending away from said scroll, and a coverconnected to said case rim to form a drive train chamber therein; saidcompressor including an impeller having a hub, a base radially extendingfrom said hub and radial vanes extending away from said hub, saidimpeller being enclosed within said air compression chamber; said casewall having a shallow bore on a first side to receive said base of saidimpeller and a case bore co-axial with said shallow bore and at leasttwo case sleeves formed on a second side; said cover having a cover boreand at least two cover sleeves formed in said cover facing said casesleeves, each being in co-axial alignment with respective case sleevesto form at least two pairs of case and cover sleeve pairs; a first pairof said case cover sleeve pairs being co-axial with said cover bore; asecond pair of said case cover sleeve pairs sleeves being co-axial withsaid case bore; an internal drive mechanism housed within said drivetrain chamber including: an endless cog belt having an inner surface, anouter surface and opposing sides; an input shaft mounted to rotate abouta first predetermined axis and having an end extending through saidcover bore and responsively connected to said engine; an input sprocketengaging said inner surface of said belt and having a hub received aboutsaid input shaft; a pair of sealed input bearings positioned on oppositesides of said input sprocket and having inner races received about saidinput shaft and outer races anchored respectively in said first pair ofsaid case and cover sleeve pairs; an input spring being bearing-loadingand shock absorbing and having a hub received about said input shaft,said spring being nested within said respective cover sleeve betweensaid case and respective input bearing; an output shaft mounted torotate about a second predetermined axis parallel to said first axis andhaving an end extending through said case bore and drivingly connectedto said impeller; an output sprocket having a hub received about saidoutput shaft and flanges radially extending from opposite sides of saidoutput sprocket and being inclined away from each other, said innersurface of said belt engaging said output sprocket between said flanges;a pair of sealed output bearings positioned on opposite sides of saidoutput sprocket and having inner races received about said output shaftand outer races anchored respectively in said second pair of said caseand cover sleeve pairs; a bearing-loading shock absorber nested withinsaid respective cover sleeve between said respective output bearing andsaid cover including a spacer contacting said respective output bearingand an input spring being bearing-loading and shock absorbing andcontacting said spacer and said cover; said output shaft including atleast one air channel formed circumferentially about said output shaft;said output sprocket including at least one set of air vents radiallyformed in said output sprocket and aligned with said at least one airchannel to form an air duct such that air trapped between said outputsprocket and belt is evacuated out through said air duct; an idlerhaving a idler shaft mounted to rotate about an axis normal to saidsides of said belt and an idler pulley displacingly engaging said outersurface of said belt; said idler shaft having one end anchored to saidcase; and at least one shim received about said output shaft between anoutput shaft shoulder and said impeller such that an impeller clearanceis established to improve efficiency and air flow.
 2. An air compressorapparatus for use as a supercharger in a combustion engine comprising: ahousing secured to said engine, having an air inlet, an air outletconnected to said engine, an air compression chamber formed therein anda drive train chamber formed therein; an impeller having a hub andradial vanes extending away from said hub, said impeller being enclosedwithin said air compression chamber; a case wall separating said aircompression chamber and drive train chamber, having a shallow bore on afirst side receiving said impeller and a bore co-axial with said shallowbore extending between said air compression and drive train chambers; aninternal drive mechanism connected within said drive train chamberincluding: an endless cog belt having an inner surface and teeth formedon said inner surface; an input shaft mounted to rotate about apredetermined axis and having an end extending through said housing andresponsively connected to said engine; an input sprocket having teethengaging said teeth on said inner surface of said belt and a hubreceived about said input shaft; a pair of sealed input bearingspositioned on opposite sides of said input sprocket and having innerraces received about said input shaft and outer races connected to saidhousing; an input spring loadingly engaging one of said input bearingssaid spring being nested between said housing and said one of said inputbearings; an output shaft mounted to rotate about a second predeterminedaxis parallel to said first axis and having an end extending throughsaid wall bore and drivingly connected to said impeller; and an outputsprocket having a hub received about said output shaft, teeth formedabout said output sprocket, and flanges radially extending from oppositesides of said output sprocket and being inclined away from each other,said teeth of said inner surface of said belt engaging said teeth ofsaid output sprocket between said flanges; a pair of sealedpre-lubricated output bearings positioned on opposite sides of saidoutput sprocket and having inner races received about said output shaftand outer races connected to said housing; a shock absorber loadinglyengaging one of said output bearings between said one of said outputbearings and said housing including a spacer contacting said one of saidoutput bearings and shock absorbing output spring nested between saidspacer and said housing; said output shaft including at least one airchannel formed circumferentially about said output shaft; said outputsprocket including at least one set of air vents radially formed in saidoutput sprocket and aligned with said at least one air channel to forman air duct; an idler having an idler shaft mounted to rotate about anaxis parallel to said input and output shafts and an idler pulleydisplacingly engaging said outer surface of said belt; said idler shafthaving one end anchored to said housing.
 3. In an air compressorapparatus, an internal drive mechanism including: input and outputshafts; input and output sprockets mounted, respectively; on said inputand output shafts; an endless belt trained around and drivinglyconnected to said input and output sprockets; said belt being a positivedrive cog belt and said sprockets being positive drive cog sprocketsmating with said belt; and sealed, pre-lubricated ball bearings havinginner races for receiving said output shaft therein.
 4. The internaldrive mechanism of claim 3 wherein said bearings are heat resistant. 5.The internal drive mechanism of claim 3 wherein said bearings areceramic.
 6. In an air compressor apparatus, an internal drive mechanismincluding: input and output shafts; input and output sprockets mounted,respectively, on said input and output shafts; an endless belt trainedaround and drivingly connected to said input and output sprockets; saidbelt being a positive drive cog belt and said sprockets being positivedrive cog sprockets mating with said belt; and stabilizing means forstabilizing tension applied to said belt during rotation.
 7. Theinternal drive mechanism of claim 6 wherein said stabilizing meansincludes: sealed, pre-lubricated ball bearings having inner racesreceiving said output shaft therein; tensioning members formed withinsaid belt; air ducts formed within said output sprocket; at least onespring mounted adjacent to one of said bearings; and an idler engaginglyconnected to said belt.
 8. The internal drive mechanism of claim 6wherein said stabilizing means includes: heat resistant ball bearingshaving inner races receiving said output shaft therein; evacuating meansfor evacuating air between said belt and said output sprocket; andtensioning members formed within said belt.
 9. The internal drivemechanism of claim 6 wherein said stabilizing means includes: ceramicball bearings having inner races receiving said output shaft therein;and black fiberglass tensioning members formed within said belt.
 10. Inan air compressor apparatus, an internal drive mechanism including:input and output shafts; input and output sprockets mounted,respectively, on said input and output shafts; an endless belt trainedaround and drivingly connected to said input and output sprockets; saidbelt being a positive drive cog belt and said sprockets being positivedrive cog sprockets mating with said belt; and wherein said beltincludes black fiber glass tensioning members.
 11. In an air compressorapparatus, an internal drive mechanism including: input and outputshafts; input and output sprockets mounted, respectively, on said inputand output shafts; an endless belt trained around and drivinglyconnected to said input and output sprockets; said belt being a positivedrive cog belt and said sprockets being positive drive cog sprocketsmating with said belt; and evacuating means for evacuating air trappedbetween said output sprocket and said belt.
 12. The internal drivemechanism of claim 11 wherein: said venting means includes air ductsformed in the output sprocket.
 13. The internal drive mechanism of claim11 wherein said air ducts include: air vents radially formed in saidoutput sprocket; and at least one air channel formed about thecircumference of said output shaft.
 14. In an air compressor apparatus,an internal drive mechanism including: input and output shafts; inputand output sprockets mounted, respectively, on said input and outputshafts; an endless belt trained around and drivingly connected to saidinput and output sprockets; said belt being a positive drive cog beltand said sprockets being positive drive cog sprockets mating with saidbelt; and an idler responsively engaging said belt and disposed inrelation to said input and output sprockets on a load side.
 15. In anair compressor apparatus, an internal drive mechanism including: inputand output shafts; input and output sprockets mounted, respectively, onsaid input and output shafts; an endless belt trained around anddrivingly connected to said input and output sprockets; said belt beinga positive drive cog belt and said sprockets being positive drive cogsprockets mating with said belt; and sealed, pre-lubricated ballbearings having inner races for receiving said output shaft therein; afinger spring loadingly engaging one of said bearings.